T Tauri stars are believed to be young, high-mass main-sequence stars.
a. True
b. False
Indicate whether the statement is true or false
Question 2Poor clusters
a. contain more than 1000 stars and are found in the halo of the galaxy.
b. contain lots of young stars and are found in the disk of a spiral galaxy.
c. contain more than 1000 galaxies and are generally elliptical in shape.
d. contain fewer than 1000 galaxies and tend to be irregularly shaped.
e. are found in the nucleus of the galaxy.
Question 3The Orion region contains young main-sequence stars and an emission nebula, but the original molecular cloud they formed out of has been dispersed.
a. True
b. False
Indicate whether the statement is true or false
Question 4Gravitational lensing
a. occurs when light passes near a massive object and is deflected by the object's gravitational field.
b. can be used to determine the luminosity of a galaxy.
c. occurs when the mass of a galaxy is greater than expected from the luminosity of the galaxy.
d. occurs when the mass of a galaxy is less than expected from the luminosity of the galaxy.
e. can be used to determine the recessional velocity of a galaxy.